1. Field
The present specification generally relates to optical fibers and, more specifically, to optical fibers with large effective areas and reduced non-linearity.
2. Technical Background
Optical amplifiers and wavelength division multiplexing (WDM) techniques are typically utilized in optical telecommunications systems that provide high power transmissions over long distances. The definition of high power and long distances is meaningful only in the context of a particular telecommunications system wherein a bit rate, a bit error rate, a multiplexing scheme, and perhaps optical amplifiers are specified. In general, fiber nonlinearity is a fundamental limiting factor to such high speed, long haul, WDM telecommunications systems. For example, in some applications, single power levels of 1 mW or less propagated in an optical fiber may be sensitive to non-linear effects, including self-phase modulation, four-wave mixing, cross-phase modulation, and non-linear scattering processes. Each of these non-linear effects can cause the degradation of optical signals propagating in the WDM telecommunications systems.
Fiber nonlinearity can be reduced by increasing the effective area of the optical fiber as the power density of the optical fiber is inversely proportional to the effective area. However, an increase in the effective area of an optical fiber typically results in an increase in the induced bending losses (both micro and macro) and, as a result, the attenuation of the optical signal propagating in the optical fiber. Accordingly, the ability to reduce the non-linearity of conventional single-mode transmission optical fibers by increasing the effective area of the fiber is limited by the corresponding increase in bending losses for the fundamental mode of the optical signal propagating in the fiber.
Accordingly, a need exists for alternative designs for transmission optical fibers with reduced nonlinearity and bending losses.